Perimeter And Area Of A Circle

/*
 * Write a program that reads the radius r of a circle and prints its perimeter and area.
*/

using System;

class PerimeterAndAreaOfACircle
{
    static void Main()
    {
        double radius, perimeter, area;

        string invalidInput = "Invalid input! Please enter value between 0 and " + double.MaxValue + "!\r\n";

        Console.WriteLine("enter value for radius of a circle r = ");
        while (!(double.TryParse(Console.ReadLine(), out radius) && radius > 0 && radius <= double.MaxValue))
        {
            Console.WriteLine(invalidInput + "\r\nenter value for radius of a circle r = ");
        }
        checked { perimeter = 2 * Math.PI * radius; }
        checked { area = Math.PI * (radius * radius); }

        Console.WriteLine("\r\nResults:\r\nperimeter = {0}\r\narea = {1}\r\n", perimeter, area);
        Main();
    }
}